1 files changed, 272 insertions, 0 deletions
diff --git a/firmware/lib20/common.c b/firmware/lib20/common.c
new file mode 100644
index 00000000..9ce9d840
--- /dev/null
+++ b/firmware/lib20/common.c
@@ -0,0 +1,272 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Common functions between firmware and kernel verified boot.
+ * (Firmware portion)
+ */
+
+#include "2sysincludes.h"
+#include "2rsa.h"
+#include "2sha.h"
+#include "vb2_common.h"
+
+uint8_t *vb2_signature_data(struct vb2_signature *sig)
+{
+	return (uint8_t *)sig + sig->sig_offset;
+}
+
+int vb2_verify_member_inside(const void *parent, size_t parent_size,
+			     const void *member, size_t member_size,
+			     ptrdiff_t member_data_offset,
+			     size_t member_data_size)
+{
+	const uintptr_t parent_end = (uintptr_t)parent + parent_size;
+	const ptrdiff_t member_offs = vb2_offset_of(parent, member);
+	const ptrdiff_t member_end_offs = member_offs + member_size;
+	const ptrdiff_t data_offs = member_offs + member_data_offset;
+	const ptrdiff_t data_end_offs = data_offs + member_data_size;
+
+	/* Make sure parent doesn't wrap */
+	if (parent_size < 0 || parent_end < (uintptr_t)parent)
+		return VB2_ERROR_INSIDE_PARENT_WRAPS;
+
+	/*
+	 * Make sure the member is fully contained in the parent and doesn't
+	 * wrap.  Use >, not >=, since member_size = 0 is possible.
+	 */
+	if (member_size < 0 || member_end_offs < member_offs)
+		return VB2_ERROR_INSIDE_MEMBER_WRAPS;
+	if (member_offs < 0 || member_offs > parent_size ||
+	    member_end_offs > parent_size)
+		return VB2_ERROR_INSIDE_MEMBER_OUTSIDE;
+
+	/* Make sure the member data is after the member */
+	if (member_data_size > 0 && data_offs < member_end_offs)
+		return VB2_ERROR_INSIDE_DATA_OVERLAP;
+
+	/* Make sure parent fully contains member data, if any */
+	if (member_data_size < 0 || data_end_offs < data_offs)
+		return VB2_ERROR_INSIDE_DATA_WRAPS;
+	if (data_offs < 0 || data_offs > parent_size ||
+	    data_end_offs > parent_size)
+		return VB2_ERROR_INSIDE_DATA_OUTSIDE;
+
+	return VB2_SUCCESS;
+}
+
+int vb2_verify_signature_inside(const void *parent,
+				uint32_t parent_size,
+				const struct vb2_signature *sig)
+{
+	return vb2_verify_member_inside(parent, parent_size,
+					sig, sizeof(*sig),
+					sig->sig_offset, sig->sig_size);
+}
+
+int vb2_verify_digest(const struct vb2_public_key *key,
+		      struct vb2_signature *sig,
+		      const uint8_t *digest,
+		      const struct vb2_workbuf *wb)
+{
+	uint8_t *sig_data = vb2_signature_data(sig);
+
+	if (sig->sig_size != vb2_rsa_sig_size(key->sig_alg)) {
+		VB2_DEBUG("Wrong data signature size for algorithm, "
+			  "sig_size=%d, expected %d for algorithm %d.\n",
+			  sig->sig_size, vb2_rsa_sig_size(key->sig_alg),
+			  key->sig_alg);
+		return VB2_ERROR_VDATA_SIG_SIZE;
+	}
+
+	return vb2_rsa_verify_digest(key, sig_data, digest, wb);
+}
+
+int vb2_verify_data(const uint8_t *data,
+		    uint32_t size,
+		    struct vb2_signature *sig,
+		    const struct vb2_public_key *key,
+		    const struct vb2_workbuf *wb)
+{
+	struct vb2_workbuf wblocal = *wb;
+	struct vb2_digest_context *dc;
+	uint8_t *digest;
+	uint32_t digest_size;
+	int rv;
+
+	if (sig->data_size > size) {
+		VB2_DEBUG("Data buffer smaller than length of signed data.\n");
+		return VB2_ERROR_VDATA_NOT_ENOUGH_DATA;
+	}
+
+	/* Digest goes at start of work buffer */
+	digest_size = vb2_digest_size(key->hash_alg);
+	if (!digest_size)
+		return VB2_ERROR_VDATA_DIGEST_SIZE;
+
+	digest = vb2_workbuf_alloc(&wblocal, digest_size);
+	if (!digest)
+		return VB2_ERROR_VDATA_WORKBUF_DIGEST;
+
+	/* Hashing requires temp space for the context */
+	dc = vb2_workbuf_alloc(&wblocal, sizeof(*dc));
+	if (!dc)
+		return VB2_ERROR_VDATA_WORKBUF_HASHING;
+
+	rv = vb2_digest_init(dc, key->hash_alg);
+	if (rv)
+		return rv;
+
+	rv = vb2_digest_extend(dc, data, sig->data_size);
+	if (rv)
+		return rv;
+
+	rv = vb2_digest_finalize(dc, digest, digest_size);
+	if (rv)
+		return rv;
+
+	vb2_workbuf_free(&wblocal, sizeof(*dc));
+
+	return vb2_verify_digest(key, sig, digest, &wblocal);
+}
+
+int vb2_verify_keyblock(struct vb2_keyblock *block,
+			uint32_t size,
+			const struct vb2_public_key *key,
+			const struct vb2_workbuf *wb)
+{
+	struct vb2_signature *sig;
+	int rv;
+
+	/* Sanity checks before attempting signature of data */
+	if(size < sizeof(*block)) {
+		VB2_DEBUG("Not enough space for key block header.\n");
+		return VB2_ERROR_KEYBLOCK_TOO_SMALL_FOR_HEADER;
+	}
+	if (memcmp(block->magic, KEY_BLOCK_MAGIC, KEY_BLOCK_MAGIC_SIZE)) {
+		VB2_DEBUG("Not a valid verified boot key block.\n");
+		return VB2_ERROR_KEYBLOCK_MAGIC;
+	}
+	if (block->header_version_major != KEY_BLOCK_HEADER_VERSION_MAJOR) {
+		VB2_DEBUG("Incompatible key block header version.\n");
+		return VB2_ERROR_KEYBLOCK_HEADER_VERSION;
+	}
+	if (size < block->keyblock_size) {
+		VB2_DEBUG("Not enough data for key block.\n");
+		return VB2_ERROR_KEYBLOCK_SIZE;
+	}
+
+	/* Check signature */
+	sig = &block->keyblock_signature;
+
+	if (vb2_verify_signature_inside(block, block->keyblock_size, sig)) {
+		VB2_DEBUG("Key block signature off end of block\n");
+		return VB2_ERROR_KEYBLOCK_SIG_OUTSIDE;
+	}
+
+	/* Make sure advertised signature data sizes are sane. */
+	if (block->keyblock_size < sig->data_size) {
+		VB2_DEBUG("Signature calculated past end of block\n");
+		return VB2_ERROR_KEYBLOCK_SIGNED_TOO_MUCH;
+	}
+
+	VB2_DEBUG("Checking key block signature...\n");
+	rv = vb2_verify_data((const uint8_t *)block, size, sig, key, wb);
+	if (rv) {
+		VB2_DEBUG("Invalid key block signature.\n");
+		return VB2_ERROR_KEYBLOCK_SIG_INVALID;
+	}
+
+	/* Verify we signed enough data */
+	if (sig->data_size < sizeof(struct vb2_keyblock)) {
+		VB2_DEBUG("Didn't sign enough data\n");
+		return VB2_ERROR_KEYBLOCK_SIGNED_TOO_LITTLE;
+	}
+
+	/* Verify data key is inside the block and inside signed data */
+	if (vb2_verify_packed_key_inside(block, block->keyblock_size,
+					 &block->data_key)) {
+		VB2_DEBUG("Data key off end of key block\n");
+		return VB2_ERROR_KEYBLOCK_DATA_KEY_OUTSIDE;
+	}
+	if (vb2_verify_packed_key_inside(block, sig->data_size,
+					 &block->data_key)) {
+		VB2_DEBUG("Data key off end of signed data\n");
+		return VB2_ERROR_KEYBLOCK_DATA_KEY_UNSIGNED;
+	}
+
+	/* Success */
+	return VB2_SUCCESS;
+}
+
+int vb2_verify_fw_preamble(struct vb2_fw_preamble *preamble,
+			   uint32_t size,
+			   const struct vb2_public_key *key,
+			   const struct vb2_workbuf *wb)
+{
+	struct vb2_signature *sig = &preamble->preamble_signature;
+
+	VB2_DEBUG("Verifying preamble.\n");
+
+	/* Sanity checks before attempting signature of data */
+	if(size < sizeof(*preamble)) {
+		VB2_DEBUG("Not enough data for preamble header\n");
+		return VB2_ERROR_PREAMBLE_TOO_SMALL_FOR_HEADER;
+	}
+	if (preamble->header_version_major !=
+	    FIRMWARE_PREAMBLE_HEADER_VERSION_MAJOR) {
+		VB2_DEBUG("Incompatible firmware preamble header version.\n");
+		return VB2_ERROR_PREAMBLE_HEADER_VERSION;
+	}
+
+	if (preamble->header_version_minor < 1) {
+		VB2_DEBUG("Only preamble header 2.1+ supported\n");
+		return VB2_ERROR_PREAMBLE_HEADER_OLD;
+	}
+
+	if (size < preamble->preamble_size) {
+		VB2_DEBUG("Not enough data for preamble.\n");
+		return VB2_ERROR_PREAMBLE_SIZE;
+	}
+
+	/* Check signature */
+	if (vb2_verify_signature_inside(preamble, preamble->preamble_size,
+					sig)) {
+		VB2_DEBUG("Preamble signature off end of preamble\n");
+		return VB2_ERROR_PREAMBLE_SIG_OUTSIDE;
+	}
+
+	/* Make sure advertised signature data sizes are sane. */
+	if (preamble->preamble_size < sig->data_size) {
+		VB2_DEBUG("Signature calculated past end of the block\n");
+		return VB2_ERROR_PREAMBLE_SIGNED_TOO_MUCH;
+	}
+
+	if (vb2_verify_data((const uint8_t *)preamble, size, sig, key, wb)) {
+		VB2_DEBUG("Preamble signature validation failed\n");
+		return VB2_ERROR_PREAMBLE_SIG_INVALID;
+	}
+
+	/* Verify we signed enough data */
+	if (sig->data_size < sizeof(struct vb2_fw_preamble)) {
+		VB2_DEBUG("Didn't sign enough data\n");
+		return VB2_ERROR_PREAMBLE_SIGNED_TOO_LITTLE;
+	}
+
+	/* Verify body signature is inside the signed data */
+	if (vb2_verify_signature_inside(preamble, sig->data_size,
+					&preamble->body_signature)) {
+		VB2_DEBUG("Firmware body signature off end of preamble\n");
+		return VB2_ERROR_PREAMBLE_BODY_SIG_OUTSIDE;
+	}
+
+	/* Verify kernel subkey is inside the signed data */
+	if (vb2_verify_packed_key_inside(preamble, sig->data_size,
+					 &preamble->kernel_subkey)) {
+		VB2_DEBUG("Kernel subkey off end of preamble\n");
+		return VB2_ERROR_PREAMBLE_KERNEL_SUBKEY_OUTSIDE;
+	}
+
+	/* Success */
+	return VB2_SUCCESS;
+}